<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			var a=2,b=1,c=a/b;
			for ( var i=1;i<=20;i++) {
				sum=a+b;
				b=a;
				a=sum;
				c+=a/b
			}
			console.log(c)
		</script>
	</body>
</html>
